The oil and gas exploration and production industry is likely to drill and produce deeper and hotter wells, with wells with a reservoir temperature above 150° C. forecast to increase. In general, these types of wells are considered a high pressure high temperature, or HPHT, environments. In addition, an increasing number of Ultra HPHT (high pressure high temperature with the temperature above 205° C.) wells are likely to be drilled in the future. Using conventional technologies, downhole tools experience high failure rates at temperatures above 160° C. At this time, there is a limited catalog of electronic components which can reliably operate above 150° C. Therefore, providing active/passive cooling for electronics is one of the options for extending the operation and reliability of downhole tools such that they may be more effectively used in HPHT and Ultra-HPHT regimes.
Passive methods of cooling downhole tools provide cooling for a short duration as they provide a fixed capacity for heat absorption from the tool. If the tool is likely to be exposed to HPHT or ultra HPHT conditions for long duration, then active cooling methods need to be used. Active cooling methods use electric power to reject heat absorbed from the tool at lower temperatures to the wellbore fluid (or the formation) at a higher temperature.